Seestar wrapup

 Six mostly clear nights have allowed a thorough test of the Seestar S50 in equatorial mode.  Operation of the Seestar is ridiculously easy.  Some initial manual manipulation is required to get the polar axis aligned.  This process is helped along by the Seestar app and takes only a couple minutes at most.  After that, the only effort required is choosing a target and deciding when to end an exposure.  The whole target-acquisition and imaging process was flawless.  All of this takes place while sitting indoors in a comfy armchair.

Here are some of my favorite images from the past few nights.  I used an Omegon cross-star filter to produce diffraction spikes that simulate the look of a Newtonian reflector.  All of these images were processed with the AI Denoise feature in the Seestar app.  Sky brightness has generally been in the range of 21.3 to 21.45 mpsas.

M81 and M82 (Bode's Nebulae) in Ursa Major. 24.3 min

 

IC 1805, middle of the Heart Nebula in Cassiopeia. 25.5 min

M34, an open cluster in Perseus.  11.8 min

M39, an open cluster in Cygnus. 13.0 min

M74, a spiral galaxy in Pisces. 24.7 min

M103, an open cluster in Cassiopeia. 17.8 min

NGC 253, a spiral galaxy in Sculptor. 25.0 min

NGC 7635, the Bubble Nebula in Cassiopeia. 22.8 min

And, almost forgot this one.  Added a day later:

 

NGC 7293, the Helix Nebula in Aquarius. 29.8 min

Morning Star in November

 Venus is now the Morning Star.  At magnitude -4.5 it is the brightest object in the sky at dawn.  The image below was captured as Venus rose over the ridgeline of Snowshoe Mountain at 6 am.  An Omegon cross-star filter was used to produce the diffraction spikes.  The star below Venus is Spica (α Virginis).  Spica is the 16th brightest star.

Venus rising over Snowshoe Mountain

 The cross-star filter consists of two 0.3-mm perpendicular wires.  It creates diffraction spikes that mimic those typically produced by the secondary-mirror vanes in Newtonian or Cassegrain telescopes.

Cross-star filter mounted on an Olympus 40-150mm f/4 lens.

 

Armchair astrophotography with the Seestar S50

 The Seestar S50 is a self-contained robotic astro-imaging system.   Once the telescope is physically setup and powered on, it can be controlled via an app on a smartphone or tablet.  I use an iPad mini.  A wifi connection allows the telescope to be controlled from indoors.

When the Seestar was first introduced it operated in Alt-Az Mode only.  This mode works quite well for short exposures, but field rotation begins to limit the exposure length.  ZWO later introduced software upgrades that allowed the telescope to be set up in Equatorial Mode, which is much better for long exposures.   Over the last two nights I used the Seestar in Equatorial Mode.  I am impressed with the results.

Seestar S50 configured for Equatorial Mode operation.

 

M45, the Pleiades. 13.5 min

This image of the Pleiades illustrates one of the drawbacks of the Seestar, which is the narrow field of view.  It is too narrow to fit this cluster into a single frame.  However, it is possible to program the telescope to produce a mosaic of images in order to achieve a wider view.  This requires longer acquisition times, of course.  I have tried the mosaic-mode  in the past and it works quite well.  I did not use this extended mode for any of these images.

Here are some additional images obtained over the past few nights.  Exposure times are noted in the captions.  All images were processed with the AI-denoise feature within the Seestar app. Sky brightness was generally in the range of 21.3 to 21.4 mpsas.

M33, the Triangulum Galaxy.  25.3 min

 

M32 (lower), a satellite galaxy of the Andromeda Galaxy. 14.5 min

M110, another satellite galaxy of Andromeda. 15.2 min

M101, the Pinwheel Galaxy in Ursa Major. 10.2 min, Alt-Az mode.

NGC 6888, the Crescent Nebula in Cygnus. 20 min

NGC 6946, the FIreworks Galaxy in Cygnus. 23.5 min

Three Major and two Minor Planets

 Saturn, Uranus, and Neptune are the three outermost major planets in our solar system.  All three are currently situated for viewing mid-evening.  The two minor planets are the asteroids (2) Pallas and (4) Vesta.  These two bodies are currently in the same patch of sky as Saturn.

A Sony A7iii camera and Rokinon 35mm f/1.8 AF lens with a Hoya Softon filter were used to take the following images.

Saturn is the bright star top center.  The circled star is tau Ceti.

Saturn is currently in the constellation Cetus.  The star circled in this image is tau Ceti, the 19th closest star system.  It is 11.9 ly distant.

In this same field of view with Saturn are Neptune (the outermost major planet), and the two asteroids (2) Pallas and (4) Vesta.  Pallas and Vesta were discovered in 1802 and 1807, respectively.  Neptune wasn't discovered until nearly 40 years later, in 1846.

The following image marks the location of these three current companions to Saturn:

 Uranus, the seventh planet, is currently located between the Pleiades star cluster and the Hyades star cluster.  At magnitude 5.6, it is feasibly detectable by the naked eye in a suitably dark location (and with good eyesight).

Uranus (circled) is in the right half of the frame.

 A closer crop better reveals its location:

 Finally, a completely unrelated image, just because:

The Cygnus section of the Milky Way

 

The Summer Triangle in November, and a 120mm Takumar

 The Summer Triangle is a broad asterism consisting of three bright northern-hemisphere stars:  Vega (α Lyrae), Altair (α Aquilae), and Deneb (α Cygni).  They are, respectively, the 5th, 12th, and 19th brightest stars.  Vega and Altair straddle the Milky Way on opposite sides, while Deneb lies squarely in the middle.  In spite of its name, this asterism is still high in the sky just west of the meridian in the early evening in November.

A Sony A7iii camera, Sony FE 20mm f/1.8 G lens, and a Hoya Sparkle-6 filter were used to take the next two images:

 

The Milky Way and the Summer Triangle

In the northeast, the constellation Auriga and the Pleiades star cluster were rising through some murky clouds and strong airglow.

 At the middle top of this image is the constellation Cassiopeia and M31, the Andromeda Galaxy.  The sky brighness this evening was in the range 21.2 to 21.3 mpsas, depending on direction.

The Super-Multi-Coated Takumar 120mm f/2.8 lens is a short-telephoto screw-mount lens manufactured by Asahi Pentax from 1972 to 1976.  The following image of the constellation Lyra is a 1:2 crop from the larger frame from the Sony A7iii.  Wide open at f/2.8, the lens exhibits some minor astigmatism in the corners, and some minor purple fringing, which was cleaned up in post processing.  This cropped image mostly excludes the astigmatic corners.

The constellation Lyra with the Takumar 120mm @ f/2.8.  Vega is the bright star.

 

Election-night stars

 The sky was clear Tuesday evening, so while waiting for election returns to come in I captured some stars setting over Bristol Head and some rising over Snowshoe Mountain.  OM-5ii camera + Sigma 56mm f/1.4 lens.

 

The handle of the Big Dipper over Bristol Head. 60 s, f/1.4

The Whirlpool Galaxy, M101, shows up as a small fuzzy patch to the left and up from center.  Here is a closer crop, in which the spiral arms are just detectable:

M101

 A diffusion filter creates a more dramatic version of this scene.  The effect is a bit too strong at this focal length.

softon filter

 

Corona Borealis. softon filter

Pleiades over Snowshoe Mountain. Tiffen black pro-mist 1/8 filter, 30 sec.

Another old Russian lens: Helios 44M-7

 The Helios 44M-7 is a 58mm f/2 screw-mount lens from near the end of the Soviet era.  Based on the serial number, this copy was likely manufactured in 1992.  I tested this lens with a Sony A7iii camera.  Like the previous tests with the 50mm Super-Takumar f/1.4 and Industar f/3.5 lenses, the results here show that this lens is not well-suited for astrophotography (and there was no reason to expect otherwise). 

Here is the lens mounted on the A7iii:

 

The following star images were obtained on 31 Oct.  There was some fairly strong red airglow that night, but it has been balanced out in post-processing.  Accurate focus was confirmed with a Bahtinov mask.

f/2.0

f/2.8

f/4.0

 This lens is horrible (for stars) wide open, just like the Super-Takumar 50mm.  It starts to become acceptable at f/4 in the center of the frame, but astigmatism is still present around the edges.

Here is a crop from the last image, at f/4:

 This shows three stars in the handle of the Big Dipper over the ridge line of Bristol Head.  Just up and left of center is a fuzzy patch which is the galaxy M101, the "Pinwheel Galaxy".  Based on star separations in this image, the true focal length for this lens is calculated to be 59.0 mm.

FYI, it seems Blogger has reverted back to serving up the original files, with correct filenames, for images uploaded directly from a computer.  I hope this persists.